Rotation mechanism for hammer drills



May 2l, 1929. E. w. STEVENS ROTATION MECHANISM FOR HAMMER DRILLS QN um. GV. um. Nm. Nm

Filed Oct. l5, 1923 INVENToR EDWARD W STEVENS 'All l ATTORNEY.

15 and the rIie Patented May 2l, 1929.

UNITED STATES lne-TENTwolf1-ICE EDWARD W. STEVENS, OE DETROIT, MICHIGAN, AssreNoE To 'CHICAGO PNEUMATIO TOOL COMPANY, OE NEW YORK, N. Y., A cORPORATION OE NEW JERSEY.

ROTATION MECHANISM FOR HAMMER DRILLS.

Application filed October 15, 1923.

This invention relates to hammer drills and more particularly to themechanism for rotating the Working tool or drill steel during the drilling operation.

In hammerl drills utilizing the well known rifle bar mechanism wherein a rifle bar engages the hammer piston to effect rotation the piston as it reciprocates becomes alter, nately a driving and a driven member. In one stroke, usually the rearwardl stroke, the rifle bar is held against rotation by its pawls so that the piston is forced to follow the curved ribs of the rifle bar. On the reverse stroke of the iston the pawls are released ar is rotated by the piston which continues to rotate due to inertia. Accordingly at the end of each stroke when the piston `changes its function, there is lost motion between the various parts comprising the rotating mechanism including the riflev bar nut, the rifle bar, the pawls and the ratchet ring.

The speed of piston travel whichis great in rock drills of the hammer type together with the inertia of the piston tends to produce in effect a continuous rotation of the latter by rifle bar mechanism. This rotation is transmitted by the piston through suit-able connections to the drill steel, but the continual shifting of the driving force tends to produce rapid. wear. After wear has taken place there is marked loss of rotative power and the hammering effect produced by the backlash at the end of each stroke of the piston causes great strain upon the parts, often resulting in breakage. y i

Among the objects of the invention are to produce steady and effective rotation of drill steels in drills ofthe type described, to over- 4o come lostmotion and backlash as the piston reverses its movement, to minimize wear' and breakage of parts, and in general to improve prior devices of this character.V

In order to illustrate the invention, one concrete embodiment thereof is shown in the accompanying drawings, in which: Fig. 1 is longitudinal sectional view; Fig. 2 is a sectional view on the line 2k2 of Fig. y1; Fig. 3 is a sectionalview on the line 3--3 of Fig. 1; f

Fig. 4.- is a transverse sectional view on the line 4-4 of Fig. 1;

Fig. 5' is an `enlarged transverse sectional View on the line 5 5 of Fig. 1; and

in an impact type of'rock drill of Serial No. 668,487.

Fig. 6 is a fragmentary longitudinal sectional view similar to Fig. 1 but on the scale lof Fig. 5 showing a slightly modified formv ofthe invention.

, The invention is disclosed as incorporated 6o conventional form, except as to specific details to be hereinafter set forth. The drill comprises a cylinder 7 having a front head-8 and a rear head 9 secured in assembled relation by 65 the usual side or through bolts 10 (Figs. 2 and t). The fronthead 8 incloses a revolvable chuck 11 adapted to receive the polygonal head of a drill steel 12 and support the same in position to be struck by the hammer piston 13, which is reciprocated inthe cylin-` der 7 by fluid pressure admitted atlt (F ig.V 2) and controlled by spool valve 15 in the offset valve casing 16. The forward end Of piston 13 is ribbed to cooperate with a 75 correspondingly.grooved sleeve 17 having a driving connection with the chuck 11, so that rotation impartedl to the piston is communicated to the drill steel in the usual manner. Rotation of piston 13 is effected by the 80 usual rifle bar mechanism whichv as shown, comprises a. rifle Ybar nut 18 secured to the piston and cooperating with the rifle bar 19k which hasa bearing in the cylinder or thrust ringi20 and -is provided at its rear end `with 85 a series of pawls 21 cooperating with a ratchet ring 22 secured in a chamber in the cylinder head 9. If desired, the rifle bar and the piston y.may have an axial bore to receive a water tube 23 .mounted-in the back head 24. J0' The operation of a rock drill having the partsdesignated above is Well known, and in accordance with the'usual practice the rifle bar 19 is rotated by the piston 13 on itsv forward or workingstroke while the pawls 21 are released, but when the pist-on reverses its strokes, the pawls engage 'the ratchet ring 22 thereby holding the rifle bar against rotation and forcing the piston to rotate as it follows the grooves on the rifle bar. To 100 'overcome the play and backlash on the rotating mechanism, which inevitably results with rifie bar` mechanism when the pist-on reverses it-s vmovement, suitable means comprising the' present invention are provided 105 for maintaining a constant rotative impulse or torque upon one of the elements Of the rot-ation mechanism.r In the form of" the invention shown, this means is effectlvenpon the rifle bar, which as Indicated infFlgs. 1 110 and 6 is provided with an extension 19tL journalled in the cylinderhead 9 and having keyed to t-he end thereof a cylindrical mem ber 25` which is eccentrically disposed in a chamber 26 in the cylinder head (Fig 5), which chamber is closed in an air tight manner by a projection 27 on the back head 24. Member 25 has a plurality ot' radial grooves 2S receiving blades 29, whereby said member forms a fluid pressure motor operated by motive fluid by-passed from the main inlet 111 through a passage 30 controlled, as is the supply to valve 15, by a manually operated throttle valve 31 (Figs. 2 and 5). In the operation of this motor, the blades 29 are forced into substantially air tight contact Wit-h the Walls of the chamber 26 by pressure fluid admitted to the rear of the blades 29 by restricted passages 32, which pressure is released Vat the proper time to permit the blades to retract by a relief groove 33 communicating'With the exhaust passage 34. rlhe exhaust from the mot-or may be led by passage 311 to the forward end of the piston chamber as indicated in Fig. 1 to blow through the hollow drill steel. In the alternative form shown in Fig. (i, the exhaust passage 84: leads directly to atmosphere.

As indicated by the dra-Wings the fluid pressure motor is very small and intended to take up the play of the rifle bar produced at the reversal of the stroke of the piston, and also to assist in the rotation of the piston. To accomplish these purposes the inotor imparts its rotative impulse to the rifle bar 19 in the direction permitted by the ratchet and paivl structure. rlhis constant rotative impulse on the rifle bar is eifective in maintaining one side of each rib of the rifle bar in Contact with the corresponding sides of the ribs in the rifle nut 18 and confines the Wear to the parts thus maintained in contact.: The sides of, the ribs `of the rifle bar and nut thus maintained in contact are the sides effective to produce rotation of the piston on its back stroke at which time the rifie bar is maintained Yagainst rearward movement by the pavvls 21 engaging the teeth of the ratchet ring 22. The rotation motor resists and cushions this reverse rotation of the rifle bar and through its constant rotative impulse on the r'ilie bar, provides means in addition to the pitch of the ribs or splines on the rifle bar for rot-ating the piston. Thus thetendency of this motor vis to increase the veffectiveness of the rifle bar as a driving member for the pis ton on the latters rearward stroke. It also minimizes the driving effect of the piston on the latters forward stroke When the rifle bar is normally the Vdriven member since its function is to turn the rifle bar in t-he direction in which the piston normally rotates the Vbar on its forward stroke. In this Way the motor largely eliminates7 or entirely overcomes the lost motion and back lash at eac-h reversal of the movement ofV the piston and increases the rotation of the piston. By maintaining one side only of the ribs or splines of the bar and nut in Contact as described above it is evidentthat the rotation motor not only reduces the Wear ordinarily incurred by the usual rifle bar mechanism but it also automatically takes up all Wear thereby insuring va perfect and efficient Afunctioning of the rotating mechanism until completely vvorn out, a result not heretofore attained. By using a small fluid pressure motor with the usual anism, the advantage olt the latters positive rotating action is retained anlV its disadvantages in rapid vicar and 'lity to breakage are greatly minimized ii not entirelyV avoided. ln Vaddition the bulkincss, increased "Weight, and poor balance of drills of t-he independent rotation type due to the size of the fluid pressure motor needed for effective rotation are avoided.

From the above, it willl be apparent that the fluid pressure motor mounted as dcscribed tends to supplement by a continuous rotative impulse, the intermittent rotation afforded the piston by the rifle bar andv nut and to maintain,constantly one side ot each rib of the rifle bar against oney side of each groove inthe nut, thereby avoiding the lost motion heretofore experienced. Thus on the forward or Working stroke of Vthe .piston and during the inoperative period ot the rifle bar mechanisimthe motor tends to augment the rotative impuise imparted to the piston during its previous rearward stroke. It will be further apparent that not only are the losses in rotative efliect resulting from the backlash and lost motion at each rifie bar rotation mech- W end of the stroke greatly minimized, but n that there is also a decrease in Wear and an avoidance of destructive .strain upon the ratchet and pawl mechanism. The invention provides in effect a continuous torque motor Working in tandem` with the intermittent torque provided by rifie bar rotation.

l claim:

1. In a hammer drill, rotation mechanism for the drill bit connorising means mounted on the drill casing cooperating with the re ciprocating impact member for causing ro tation of the latter during a part of its cycle of movement, and means independent of the reciprocative movement of the member tending to augment the rotative movement of the latter.

2. In a hammer drill in which rotation of the piston is imparted to the 'drill steel., rotation mechanism for the piston comprising means cooperating Wit-h the piston to vcause rotation thereof during a. part of its cycle of movement, said means being mounted on the drill casing for rotation in one direction lll) a constant ro- Ving means cooperating with the piston to cause rotation thereof during` a part of its cycle of inovement, said means being mounted on the drill casing for rotation in one direction only, and means responsive lto fiuid pressure for applying aV constant rotative impulse to said piston.

t. In a hammer drill in which rotation otI the piston is imparted to the drill steel, rotation mechanism for the piston comprising means cooperating with the piston 'to cause rotation thereof during a part of its cycle of movement, said means being mounted on the drill casing for rotation with the piston during the remainder of its cycle of movement, and means for applying a constant rotative impulse to said piston.

5. In a hammer drill in which rotation ont the piston is imparted to the drill steel, cooperating means on the casing and on the piston for imparting rotation to the latter, and means responsive directly to fluid pressure for augmenting the rotation of the pisron. f

6. In a hammer drill in which rotation ci the piston is imparted to the drill steel,

cooperating means on the casing and on the piston ior imparting rotation toy the later during its movement in one direct-ion, and means responsive directly to fluid pressure for augmenting the rotation of the piston.

7. In a hammer drill in Whichrotation of the piston is imparted to the drill steel, cooperating members on the casing and on the hammer piston for imparting rotation' to the latter comprising a rifle bar and a rifle bar nut, and means ior taking up lost motion between said bar and nut when the piston reserves its movement.

8. In a hammer drill in Which rotation of the piston is imparted to the drill steel, cooperating members on the casing and on the piston for imparting rotation to the latter comprising a rifle bar and a. rifle bar nut, and means for applying a constant torque to one of said last named members.

9. In a hammer drill in which rotation of the piston is imparted to the drill steel, cooperating members on the casing and on the piston for imparting rotation to the latter comprising a rifle bar and a rifle bar nut, and a fluid pressure rotation motor associated with one ot' said rotation members for auginenting the rotative impulse applied to the piston.

l0. In a hammer drill, a member arranged to rotate the drill bit, a fluid pressure rotation motor :for continuously impar .ing a rotative impulse to said member in one direcagainst rotat to rotate the drill tion, and meansrestraining said member ion in the opposite direction. ll. Ina hammer drill, a member arranged bit, a fluid pressure rotation motor for continuously imparting a rotative impulse to said member in one direction, and ratchet and paivl mechanism for preventing rotation thereof in the opposite direction. v

' l2. In a hammer drill having a percussive motor'including a hammer piston, the combination With rifle bar mechanism for imparting rotation to the rhammer piston during movement thereotI in one direction,y

of, fluid pressure operated means distinct from' said percussive motor associated With said mechanism for imparting to said piston a rotative impulse `during its movement in the reverse direction.

13.'.A hammer drill comprising ya casing, a drill bit chuck rotatably mounted in the casing,a hammer piston reciprocable in said casing and having a said chuck, and means responsive both to movement of said piston in one direction and to motiveluid pressure for-rotating said piston.

14. In a hammer drill wherein the hammer piston has a driving connection With the rotatably mounted drill chuck, mechanism for causing rotation of said piston comprising in combination means intermittently imparting a rotative impulse to and means constantly imparting a rotative force thereto.

l5. A hammer drill comprising a casing, a drill bit chuck rotatably mounted therein, la hammer piston reciprocable in said casing and having a drivingv connection with said chuck, a rifle nut'on said pistoma rifley bar Von said casing cooperating WithV saidnut, ratchet and paWl mechanism restraining said bar against rotation in one direction, and means imparting a constant rotative force to said bar.v

16. A hammer drill comprising a casing, a drill bit chuck rotatably mounted therein, a hammer piston and having a driving connection With said chuck, a rilie nut on said piston, a rifle bar on said casing cooperating With said nut, ratchet and paWl mechanism restraining said bar against rotation in one direction, and

means responsive to fluid pressure for tak-` ing up lost motion between said bar and nut. 17. Ahammer drill comprising a casing, a drill bit chuck rotatably mounted therein, a

hammer piston reciprocable in said casingy and having a driving connection With said chuck, a ril'le nut on said piston, a rifle bar on said casing vcooperating With said nut, ratchet and paWl mechanism restraining said bar against rotation in one direction, a fluid pressure motor associated With said bar for imdriving connection With said piston Y reciprocable in said casing parting a constant rotative force thereto, and meansi'or directing the exhaust of said motor througha hollow drill bit supported in said chuck.

18. In a hammer drill in which rotation of the piston is imparted to the drill steel, cooperating means on the casing and on the pistonior imparting rotation to the latte iii response to its movement including a rifle bar and a rifle nut, and means confining the wear on said baixand nutto ,one side only oi' the ribs thereof. Y 19. Ina hammer drill in which rotation of the piston is imparted tothe drill steel, cooperating means on the casing and on the piston Jfor imparting rotation to the latter in response to its movement including a i'itle bar and a rifle nut, and `means automatically maintaining .contact between the same 4parts of said bar and said nutregard- 1iess of wear whereby the efiiciency of the rotative means does not diminish with use.

20. In al hammer drill in which rotation of thepiston is imparted to the drill steel, cooperating means on the casing and on the piston orimparting.rotation tothe latter in response to its movement including la rifle bar and a -yriiie nut, and `fluid pressure vi'esponsive `means automatically maintaining the same portionsiof said bar and said nut in contact regardless` of wear `whereby the eiiiciencyoi the rotative means does not diminishwith use. Y

2l. In a hammer drill in which rotation of the piston is imparted to the drill steel, cooperating means on -tlie casing and on thepiston-Ior imparting rotation to the latler in response toitsmovement including a rifle bar and a rifle nut, and means confining the wear on saidV bar and nut to one side only of the-ribs'thereoff and automatically taking mounted on y said casing,

the efficiency of the ro up all wear whereby diminish vwith tation mechanism does not use.

22. In a hammer drill in which rotation of the piston is imparted` to the drill steel, cooperating members on the casing and on the piston for imparting rotation to the later in response to is movement, said members having engaging surfaces susceptible to .vcar,

acting through certain of said of and means members to localize and reduce the wear said surfaces.

23. In a hammer drill in which rotation of the piston is imparted to the drill steel, cooperating members on the casing and on the piston for imparting rotation to the latter in response to its movement, said members having engaging surfaces susceptible to wear, and fluid pressure means acting through certain of said members to localize and reduce the wear of said surfaces.

24. A fluid pressure percussive drill com prising a casing, a drill bit chuck rotatably a hammer piston reciprocable in said casing and having a driving connection with said chuck, a rifle nut on said piston, a riie bar in said casing cooperating with said nut, ratchet and pawl mechanism restraining said bar against rovtation in one direction, and a iiuid pressure rotative motor Ain said casing rearwardly of said rifle bar and'in line therewith, said motor being arrangedto imparta continuous rotative iorce'to said rifle bar, the rotor of said motor being secured to an extension oi said rifle bar and rotating the latter in the direction permitted by said ratchet and pawl mechanism. Y

Signed by me at Detroit, Michigan, this 6th day of October, 1923.

EDWARD IN. STEVENS.

v(il) CERTIFICATE 0F CORRECTION.

Patent No. 1,713,987. Granted May 21, 1929, to

EDWARD W. STEVENS.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 3, line 44, claim 7, for the word "reserves" read "reverses"; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 2nd day of July, A. D. 1929.

M. J. Moore,

(Seal) Acting Commissioner of Patents. 

